FI70329C - ANORDINATION FOR MAINTENANCE OF SEDIMENTATIONSEGENS CAPACITY FOR FASTA AEMNESPARTIKLAR - Google Patents

Description

[• <* # *> • '1 ΓΒ1 m ^ ANNOUNCEMENT ηλ 7 λ «48H? Β utläggningsskrift / U32 9 C (45) Patent granted ^ g £ gj Patent m-PJelat 15 03 1050 (51) Kv.lk. * / Lnt.CI. 'G 01 N 15/04 FINLAND — FINLAND (21) Patent application - Patentansökning 790280 (22) Application date - Ansökningsdag 29 · 01.79 (23) Start date - Giltighetsdag 29.01.79 (41) Has become public - Blivit offentlig 25.1 0.79

Patent and Registration Office ...... ..... . . ...,.

* (44) Date of launch and issue. -

Patent and registration authorities Ansökan utlagd och utl.skriften publicerad 28.02.86 (32) (33) (31) Privilege requested - Begärd priority 24.04.78 Canada (CA) 301784 (71) Noranda Mines Limited, P.O. Box 45, Suite 4500, Commerce Court West,

Toronto, Ontario, Canada (CA) (72) Frank Rosenblum, Ville St-Laurent, Quebec, Canada (CA) (74) Leitzi nger Oy (54) Device for measuring the detection properties of tea constituents -Anordning för mätning av sedimentationsegenskaperna fasta ämnespart The present invention relates to a device for measuring the clarifying properties of solids, comprising two separate vertical housings adapted to be filled to the same level with a liquid having a density less than that of the solids to be measured, a bridge connecting the two housings close to each other to maintain the same liquid surface in the housings, means for conducting a sample of the solids to be measured to the top of the second housing, pressure sensors arranged at the bottom of the housings, measuring the pressure difference produced by the sample into the second housing and providing an output signal corresponding to the weight of the sample remaining in suspension.

A Bräs device for measuring the clarification properties of solid particles is disclosed in U.S. Patent No. 3,896,660. This device has a number of vertically spaced sensors located in the clarification tube. The vertically spaced sensors are connected to a transducer to sense the hydrostatic pressure provided by the suspension of solids in the liquid contained in such a clarification tube acting on the pressure sensors. However, the above-mentioned device has only one clarification tube and thus the absolute pressure exerted by the solid components in suspension is known. The sensitivity of such a device is low because the weight of the liquid column in the clarification tube is measured and must be subtracted from the pressure transducer reading to achieve a useful result. In addition, the above-mentioned device provides only a settling determination for dry solids, since each amount of water associated with the solids affects the readings. The device disclosed in the above-mentioned patent also uses a liquid as a pressure-transmitting medium between the sensors and the transducer, as well as a filter plate to prevent solid particles from entering the transducer. Filter plates can become clogged, rendering the device unusable.

It is therefore an object of the present invention to provide a clarification device which does not have the disadvantages of the previously known clarification devices.

The device according to the invention is characterized in that the pressure sensors consist of a flexible membrane mounted on the wall of each housing and of pipes connecting the pressure transducers of each membrane. This outlet can be used to measure the weight fraction of solids passing through a sieve of a certain mesh size or to measure the specific gravity of a known dry matter weight particulate material.

The invention will now be described by way of example with reference to a preferred embodiment illustrated in the accompanying drawings, in which:

Figure 1 shows an embodiment of a clarification device according to the invention.

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Figure 2 shows in larger size the top of the second vertical housing of the device.

Figure 3 shows a section taken along line 3-3 of Figure 1.

Figure 4 shows a clarification curve for a sample of known size distribution, which is used as a correlation parameter to determine the size distribution of a sample of unknown size distribution.

Figure 5 shows a comparison of the size distributions obtained from the screening and the device according to the invention, the sludge sample sets that were taken every half hour.

Figure 6 shows the weight% of different samples in suspension at different times from the introduction of the samples into the clarifier.

Figure 7 shows the linear relationship, as determined by previous screening analysis, between the weight% of a sample of a given size distribution and the time required for the pressure difference to decrease to 40% of the original value.

Figures 1 to 3 show an embodiment of a clarification device with two tubular vertical clarification housings with a rectangular section 14 at the bottom, respectively. 16. In the embodiment described above, both tubes, i.e. the housings, are made of plastic, e.g. Plexiglass (trademark of methyl racrate). Of course, the tubes can also be made of metal or some other suitable material. The pipes can be held in a vertical position in any conventional manner, either by leaning on the floor or being mounted on a wall.

The tubes are kept apart by spacers 18 and 20.

The upper part of the upper spacer 20 is hollow and acts as a water bridge between the tubes 10 and 12. Tube 10 is a reference tube and tube 12 is a clarification tube or vice versa and both tubes are initially filled with a reference fluid. In most applications, especially those operating with finely ground ore measurements, the suitable liquid used to fill the pipes 10 and 4 70329 12 and the smear bridge 20 is water. However, any suitable liquid having a density lower than that of the solids to be measured may be used. The tops of the tubes have openings 22 which communicate with the bridge 20 to level the surface of the liquid in both tubes. The bridge 20 is provided with partitions 24 to dampen any movement of the liquid between the tubes, and in particular when the sample is introduced into the clarification tube. Holes are made in the partitions to level the surface of the liquid in the bridge and pipes. The pipes 10 and 12 may preferably be filled through an inlet 26 made in the bottom of the pipes, and the water level is maintained via an overflow pipe 28 extending inside the bridge 20. The height, shape and cross-section of the pipes can vary and in many cases depend on the particular application.

formed by the particles of the material is normally in suspension in water, which is circulated continuously pipe 30, 34 through the hopper 32 and drop tube connected to the overflow pipe 28. The funnel 32 has an aperture which is adapted to fit the 12 end selkeytysputken, and the tube 30 is movable direction of arrow A containing solid particles to direct the slurry to the clarification tube 12 when placed to the left or directly through the outlet of the hopper 32 when it is on the right side to recycle the slurry.

A similar funnel 32 is located at the upper end of the tube 10 and connected to the overflow tube 28, because the sample to be tested can also be introduced into the tube 10 and the tube 12 can be used as a reference tube.

An insert 36 is located at the upper end of the tubes 10 or 12 to direct the slurry below the level of the bridge to prevent solid particles from entering the bridge and to prevent clogging of the holes 22 and 25. The lower end of the insert 36 has slots 38, as more clearly shown in Figure 3, to allow the water portion of the slurry to rise over the bridge and level off in both pipes.

A splash guard is located at the upper end of the pipe to which the sludge is introduced to prevent excessive vortexing of the solids in the sludge in the measuring device. The splash guard is formed by a funnel 40 having inwardly turned edges 42 and an inverted conical portion 44 secured within the funnel 70329 to allow the slurry to flow downwardly as indicated by arrows B in Figure 2.

The pressure sensing device 46 is mounted near the bottom of each pipe. These pressure sensors are mounted on the same level so that the vertical distances between the top of the water column of both pipes and the corresponding sensors are equal. In this case, pressure sensing devices of any shape can be used, and in a preferred sensing device a suitable flexible membrane is integrally mounted on the surface of the planar part of the lower end of each tube or mounted independently inside the tube. The pressure sensing devices are connected to a female differential transducer 48 via pipes 50. In this case, any commercially available transducers can be used to obtain an electronic output for appropriate detection and storage, or to further process the data. The bottom of each tube is V-shaped and is also provided with a downcomer 52 to flush out solids deposited on the bottom of the clarification tube after testing. The bottom of both tubes must also be slightly stretched through the tube inlet tube 26 to facilitate flushing after testing.

The device described above works as follows:

Before adding the sample of solids to the clarification tube 12, the control pressure, i.e. the pressure difference, between the sensing devices 46 is zero. When the sample is passed as either a dry or wet powder or slurry, the pressure guiding the liquid in the clarification tube 12 rises to a value proportional to the apparent weight of the solids in the liquid, which in turn is relative to the dry weight of the air-dry sample, as shown by the following equation:

R = K "'VV

S W

S

R = K * W (2) where R = differential pressure reading K, K '= constants W = dry solids weight Ss = solids specific gravity S = liquid specific gravity (for water: S> 1)

± j S

6 70329

The volume of water added with solids and / or the volume of water displaced by solids is evenly distributed over the part of both pipes via the bridge 20 and does not affect the control pressure, i.e. the pressure difference. The initial reading is therefore maintained until the descending particles begin to drop past the pressure hours, during which time the control pressure, i.e. the pressure difference, begins to decrease. If all the particles were allowed enough time to descend past the sensors, the control pressure, i.e. the pressure difference, would return to zero. However, only sufficient time is required for predetermined weight fractions of the particles (expressed as a percentage of the initial pressure difference) to bypass the pressure sensing devices 46 for a suitable display provided by the device of the present invention.

Figure 4 shows the clarification curve (labeled control curve) obtained from samples with the following size distribution determined by previous sieve analyzes: 86.9% to 100 mesh 69.9% to 200 mesh 53.1% to 325 mesh 47.0% to 400 mesh

The clarification curve presented above has been normalized so that the peak of the karastics corresponds to 100% of the initial control pressure, i.e. the pressure difference. This clarification curve is used to check, i.e. to calibrate, the device according to the invention, taking into account the times tj, t2, t3 and t4 in order to clarify each of the weight tractions described above. These times are used to determine the weight fraction passing through the corresponding screen size for any sample of unknown size distribution with the same specific gravity. For example, when the time for clarification is ti, the size distribution of the check curve in 100 mesh according to Figure 4 is 0.7 min. and the corresponding time 0.7 min. the present value is read from the clarification curve (measured clarity curve) of a sample with an unknown size distribution and this gives a corresponding mesh size distribution of about 90.8%. The corresponding readings for times t2 »t3 and t4 are about 78.8 wt% -200, 66.0 wt% -325, and 59.5 wt% -400 for a sample with an unknown size distribution. The aforementioned 70329 readings can be processed automatically by a suitable detection device 54 under the control of a time monitoring device 56 operating at the above-mentioned time intervals t1, t2, t3 and as shown in Fig. 1.

Figure 5 shows a comparison between the size distribution (percentage by weight of material passing through sieves 100, 200, 325 and 400 mesh) obtained by sieving (dotted lines) and the apparatus of the present invention (solid lines) for a series of sludge samples taken at 0, Every 5 hours from the slurry in the concentrator. Readings are within ± 2-3% by weight. The instrument was calibrated using the average values of 19 samples.

Other characteristics of the clarification curve can be used as correlation parameters to check the device. Thus, for example, with reference to Figure 6, clarification curves for different samples of a known size distribution with a different weight percentage of -270 mesh have been obtained using the apparatus of the present invention. From these curves, the ratio between the weight percentage of -270 mesh material in the sample and the time required to reduce the pressure difference to 40% of its original value (i.e., 40% by weight of the sample remaining in suspension) is obtained by drawing a straight line at 40% weight, as shown in Figure 6. The values obtained are plotted in Figure 7 and the time intervals were found to be linear with respect to a weight fraction of -270 mesh to determine which samples have the same specific gravity, taking into account the time taken to reach 40% of the initial pressure difference and the weight percentage reading. For example, if it takes 5 minutes for a sample of unknown size distribution to go to 40% of the initial pressure, then the weight% of this sample -270 mesh is about 63%. Other similar correspondence characteristics can be derived from other known size distributions of the same sample and these characteristics can be used to calibrate the device. Other characteristics of the clarification curve obtained with the device according to the present invention can also be used as correlation parameters, for example as an integral or differential of the curve at a certain point.

The particles can be removed from the assay system by landing them on a solid base 870329 located above the pressure sensing devices, as opposed to allowing the particles to fall past the sensing devices as described above. However, in the latter case, the settled material can be easily flushed out of the device when the device is used to automatically determine the size distribution of the sample set.

The device of the present invention can also be used to determine the specific gravity of solids particles, as can be seen from the above equation. Thus, if the dry weight of the sample is solid, the following settling ratio of the solids in the water can be derived:

Ss = _i_ (3)

1-D "R

where K "is constant and the other characters are the same as above.

The device according to the present invention automatically provides a measurement of the initial weight of the sample; the percentage by weight of the substance remaining in or suspended in the suspension can therefore be easily calculated at any time without any further measurement. In addition, the absolute weight of the sample is irrelevant and does not need to be known exactly. The advantage of the device of the present invention in performing clarification assays is that it does not require any moving parts or mechanical articulation systems. Furthermore, the device can be easily adapted to semi-continuous operation, so that mass samples can be prepared automatically in quick succession, every few minutes.

Although the invention has been shown with reference to a preferred embodiment, it is clear that various modifications may be made to such an embodiment and that the invention is not limited to this preferred embodiment. Thus, for example, devices other than the bridge 20 may be used to maintain the same level of water in both housings 10 and 12, such as outlet holes made at the same level in both pipes. Other alternatives are also within the scope of the claims.

Claims (6)

1. A device for measuring the sedimentation properties of solid particles, including two separate vertical valves (10, 12) arranged to be filled with liquid to the same level, the density of the liquid being less than the density of the solid particles to be measured, a bridge (20) joining both lids (10, 12) to one another in the vicinity of their upper part, in order to maintain in both lids the same fluid body, means for conducting a sample of the solid particles to be measured to the one upper part, in the lower portion of the wires (10, 12), pressure sensing means (46), to measure the pressure difference of the sample introduced in one sample, and to produce an output signal corresponding to the weight percent of the sample in the suspension as a function of time; characterized in that the pressure-sensing means (46) consist of an elastic membrane mounted on each wall (10, 12) wall and of pipes (50) which connect each membrane with a pressure transducer (48). 2. Apparatus according to claim 1, characterized in that the means for conducting the sample of solid particles to the upper part of one shaft consists of an insertion (36) for guiding the particles below the shaft (20) of the connecting bridge (20). . 3. Device according to claim 2, characterized in that the means for guiding the samples to the side furthermore includes a funnel (32) located in the upper part (10, 12) for receiving a sample and a tube (30) above the funnel ( 32), which tube can be moved from a position directly above the side (10, 12) to a lateral position, which is nevertheless above the funnel (32), which allows continuous circulation of solid particles containing sludge and a predetermined periodic interval for periodic sampling. . Device according to claim 2, characterized in that the means for guiding the samples to the side (10, 12)